Robert Dewey Hoskins was convicted of stalking Madonna in 1996. (Reuters)
Robert Dewey Hoskins was convicted of stalking Madonna in 1996. (Reuters)

A man who was convicted of stalking Madonna and once threatened to kill the singer has escaped from a psychiatric hospital in Los Angeles, police say.

Robert Dewey Hoskins, 54, was sentenced to 10 years in prison in 1996 after attempting to scale the walls of Madonna's home and threatened to slit her throat.

Hoskins, who is described as having "very violent tendencies" managed to walk away from the mental health facility in the Los Angeles-area community of Norwalk on Friday.

"Hoskins is highly psychotic when not taking his medication and has very violent tendencies," Los Angeles police said in a statement. "The public is being warned to notify police immediately if he is found, and to not engage him on their own."

Madonna testified against Hoskins, who has also made threats against the actress Halle Berry, during his trial in 1996, claiming she had nightmares about the homeless man from Oregon after seeing him near her home in 1995.

Madonna also said her bodyguard told her Hoskins claimed that the pair should be married and that "if he couldn't have me, he was going to slice my throat from ear to ear."

Hoskins was sent to a mental hospital in California when he was released and was eventually set free. He was arrested again in July 2011 and convicted of vandalism and sent to the psychiatric hospital in Norwalk, according to the Associated Press.